A study published by JAMA has found that giving people 500mg of Vitamin C daily, giving them 400iu of Vitamin E every other day, or providing the supplements together with Multivitamin tablets did not reduce incidence of prostate cancer (“neither vitamin E nor C supplementation reduced the risk of prostate or total cancer”). Another study, also published by JAMA, found that giving Selenium, Vitamin E, or Vitamin E and Selenium “did not prevent prostate cancer in this population of relatively healthy men” – let’s take a look at how this has been reported.
The Telegraph went with Vitamins-and-antioxidants-do-not-cut-cancer-risk; The Mail New-study-shows-supplements-dont-lower-risk-prostate-cancer; and the Scotsman Research-dents-hopes-for-vitamins. Ben Goldacre has a link on the Bad Science miniblog to the BBC report, which features Pamela Mason of HSIS.
Dr Pamela Mason, scientific advisor to the Health Supplements Information Service, said all three nutrients were essential for human health.
But she added: “Vitamins and trace elements are not intended to be used like drugs. They are intended for health maintenance and for making up dietary gaps in the population.”
But 500mg Vitamin C and 400iu Vitamin E are strengths you can buy in any supermarket or health food shop. These are the “industry standard” doses of Vitamins C and E – if Pamela Mason thinks that these doses are drug-like and not intended for health maintenance and for making up dietary gaps in the population then why on earth is she speaking on behalf of the vitamin pill industry which provides these dosage strengths? The people in the study were using these pills for health maintenance in order to lower their risk of developing diseases such as prostate cancer. Where did they get the idea that Selenium and vitamins C & E might prevent prostate cancer? From nutritionistas and the food supplements industry – the very same people Pamela Mason is speaking for, in other words. Given that the Cochrane review of antioxidant supplements found that some were likely to increase the risk of various cancers and that the current studies were looking at the antioxidant nutrients given a “clean slate” by the Cochrane review (i.e., the Cochrane review didn’t find evidence that Vit C or Selenium raised cancer risk), it seems increasingly unlikely that benefits of antioxidant supplements in prevention of cancer will ever be seen in a decent-size trial.
Physicians’ Health Study II – looks at Vitamins C and E in prevention of cancers.
Editorial – includes this snippet: “SELECT had a simple, cost-effective design, completed accrual of more than 35 000 participants ahead of schedule—making it the largest individually randomized cancer prevention trial ever conducted—and maintained high rates of adherence and retention for 4 to 7 years. Given its statistical power, it is unlikely that the study missed detecting a benefit of even a very modest size. The PHS II, with more than 14 000 male physicians, was also remarkably well conducted and was especially noteworthy for its cost-efficiency, with most of the study having been conducted through the mail.” [My bold]
More, more, more…
The Cochrane review of antioxidant supplements looked at the effect of Vitamins A, C, and E, Beta Carotene, Selenium on mortality. The conclusions were not what the food supplements industry wanted to hear. “We found no evidence to support antioxidant supplements for primary or secondary prevention. Vitamin A, beta-carotene, and vitamin E may increase mortality. Future randomised trials could evaluate the potential effects of vitamin C and selenium for primary and secondary prevention. Such trials should be closely monitored for potential harmful effects. Antioxidant supplements need to be considered medicinal products and should undergo sufficient evaluation before marketing.”
The Health Food Manufacturers’ Association (HFMA – an industry association like HSIS or IANT) were moved to offer a rebuttal to the Cochrane review. You can read more about Carole Caplin and Cliff Richard’s expert views on antioxidant supplements here, on the brilliant badscienceblogs.net: Cliff Richard. If you find Carole Caplin convincing, then you could also try here: Supplementation with omega-3 fish oils is vital.
And finally, there was a post a month ago on Holford Watch that predicted the industry responses [EDIT: to a similar study in JAMA] – “not high enough doses” and “excessive doses” are both in there. I reckon this is where Pamela Mason got the idea for her response.